This invention relates to printing machines, and in particular to a multicolor screen printer for printing on fabrics, paper, and other similar materials.
Screen printing comprises fixing a piece of material to be printed upon a platen or other suitable surface, placing a silk screen on the material, and then transferring dye or ink through the screen onto the fabric by means of a roller or squeegee. When several colors are to be printed on the same piece of material, a separate screen is used for each color, and the colors are printed sequentially over one another, thereby requiring proper registry between the various screens to achieve a neat, clear, multicolored pattern which can be reproduced rapidly and reliably.
In custom printing shops, such as those specializing in the printing of indicia onto T-shirts, as well as other relatively low volume screen printing enterprises, the number of articles to be printed with a particular design at one time is typically very small. Hence, it is preferable that screen printers used in this specialized industry be highly adaptable, and capable of printing different styles and shapes of articles with a wide variety of colored patterns. Heretofore, such printing machines have been relatively large, complicated, and expensive, and are not easily adjustable to accomodate different printing requirements, particularly for low volume runs. For example, some such machines have rotating heads for rotating different screens into printing position above the printing platen. The thrust bearing assembly has to be an expensive, precision unit to insure that rotation will not lead to misalignment. One problem, even with expensive machinery, is that it is complicated or practically impossible to adjust or readjust the point on the platen at which printing takes place. The adjustment of one screen requires readjustment and reregistration of all the other screens.